Synthesis and characterization of Group 4 metallocene complexes with two disiloxanediyl bridges

Group 4 metallocene complexes with two disiloxanediyl bridges [mu,mu-(Me2Si OSiMe2)(2)(C5H3)(2)]ZrCl2 (3) and [mu,mu- (Me2SiOSiMe2)(2)(C5H3)(2)]HfCl2 ( 4) have been prepared by the reaction of MCl4 (M = Zr, Hf) with distannylat ed bis(cyclopentadienes), while the zirconium complex, 3, was subjected to a single-crystal X-ray diffraction study. The reaction of TiCl4 with two eq uivalents of doubly disiloxane bridged distannylated bis(cyclopentadienes) gives rise to the formation of the doubly bridged dinuclear titanocene [mu, mu-(Me2SiOSiMe2)(2)(C5H3)(2)][TiCl3](2) (5), Methylation and benzylation of the complex 3 results in [mu,mu-(Me2SiOSiMe2)(2)(C5H3)(2)]ZrMe2 (6) and [m u,mu-(Me2SiOSiMe2)(2)(C5H3)(2)]-Zr(CH2C6H5)(2) (7), respectively, without c omplications. Furthermore, the dibridged zirconium compound 3 polymerizes e thylene very efficiently in the presence of methylaluminoxane with an activ ity of 5 ton of PE/[Z] mol h atm. (C) 2000 Elsevier Science S.A. All rights reserved.